U.S. patent application number 10/315427 was filed with the patent office on 2003-05-01 for radio frequency data communications device with adjustable receiver sensitivity and method.
Invention is credited to Tuttle, John R., Tuttle, Mark E..
Application Number | 20030080853 10/315427 |
Document ID | / |
Family ID | 26696980 |
Filed Date | 2003-05-01 |
United States Patent
Application |
20030080853 |
Kind Code |
A1 |
Tuttle, Mark E. ; et
al. |
May 1, 2003 |
Radio frequency data communications device with adjustable receiver
sensitivity and method
Abstract
An adjustable radio frequency data communications device has a
monolithic semiconductor integrated circuit with integrated
circuitry, interrogation receiving circuitry provided on the
monolithic integrated circuit forming at least part of the
integrated circuitry and configured to receive an interrogation
signal from the interrogator unit, an antenna electrically coupled
to the interrogation receiving circuitry and configured to
communicate with the remote interrogator unit, a power source
electrically coupled to the integrated circuitry and configured to
generate operating power for the communications device, and at
least one of the antenna and the interrogation receiving circuitry
having reconfigurable electrical characteristics, the electrical
characteristics being reconfigurable to selectively tune the at
least one of the antenna and the interrogation receiving circuitry
within a range of tuned and detuned states to realize a desired
receiver sensitivity of the communications device. Additionally, a
method for tuning receiver sensitivity and/or transmitter
sensitivity according to construction of the above device is
disclosed.
Inventors: |
Tuttle, Mark E.; (Boise,
ID) ; Tuttle, John R.; (Boise, ID) |
Correspondence
Address: |
WELLS ST. JOHN ROBERTS GREGORY & MATKIN P.S.
601 W. FIRST AVENUE
SUITE 1300
SPOKANE
WA
99201-3828
US
|
Family ID: |
26696980 |
Appl. No.: |
10/315427 |
Filed: |
December 9, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10315427 |
Dec 9, 2002 |
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09961204 |
Sep 21, 2001 |
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6509837 |
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09961204 |
Sep 21, 2001 |
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08708164 |
Aug 29, 1996 |
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6466131 |
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60023321 |
Jul 30, 1996 |
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Current U.S.
Class: |
340/10.1 |
Current CPC
Class: |
G01S 13/767 20130101;
G01S 13/78 20130101; G06K 19/0723 20130101; H01Q 7/00 20130101;
G06K 19/0726 20130101; H01L 23/645 20130101; G06K 7/10346 20130101;
G06K 19/07749 20130101; Y10T 29/49016 20150115; H01Q 1/2225
20130101 |
Class at
Publication: |
340/10.1 |
International
Class: |
H04Q 005/22 |
Claims
1. An adjustable radio frequency data communications device for use
with a remote interrogator unit, the device comprising: a
monolithic semiconductor integrated circuit having integrated
circuitry; interrogation receiving circuitry provided on the
monolithic integrated circuit forming at least part of the
integrated circuitry and configured to receive an interrogation
signal from the interrogator unit; an antenna electrically coupled
to the interrogation receiving circuitry and configured to
communicate with the remote interrogator unit; a power source
electrically coupled to the integrated circuitry and configured to
generate operating power for the communications device; and at
least one of the antenna and the interrogation receiving circuitry
having reconfigurable electrical characteristics, the electrical
characteristics being reconfigurable to selectively tune the at
least one of the antenna and the interrogation receiving circuitry
within a range of tuned and detuned states to realize a desired
receiver sensitivity of the communications device.
2. The device of claim 1 further comprising transmitter circuitry
provided on the monolithic integrated circuit, the transmitter
circuitry and the interrogation receiving circuitry forming a
transponder circuit configured in combination with the antenna for
communicating with the interrogator unit.
3. The device of claim 2 wherein the transmitter circuitry further
comprises reconfigurable electrical characteristics, the
transmitter electrical characteristics being reconfigurable to
selectively tune the transmitter circuitry within a range of tuned
and detuned states to realize a desired transmitter sensitivity of
the communications device.
4. The device of claim 1 further comprising a plurality of leaded
ports provided in electrical communication with the interrogation
receiving circuitry on the integrated circuit, the antenna
comprising a hybrid element separate from the monolithic integrated
circuit, the antenna being bonded to the leaded ports to
electrically couple the antenna to the interrogation receiving
circuitry.
5. The device of claim 1 wherein the antenna comprises a separate
hybrid element, the antenna being wire bonded to the integrated
circuit in electrical communication with the interrogation
receiving circuitry.
6. The device of claim 1 wherein the antenna has the reconfigurable
electrical characteristics selectively tunable to realize a desired
receiver sensitivity of the communications device.
7. The device of claim 6 wherein the antenna is constructed and
arranged to be selectively detunable to realize the desired
receiver sensitivity.
8. The device of claim 6 wherein the antenna is constructed and
arranged to be selectively laser trimmed to realize one of a
plurality of tuned states.
9. The device of claim 8 wherein the antenna comprises a contiguous
piece of conductive microstrip, a region of the microstrip being
constructed and arranged to facilitate removal thereof to change
impedance of the antenna.
10. The device of claim 9 wherein the region is laser trimmed.
11. The device of claim 9 wherein the microstrip comprises a
removed region, the removed region providing a width change in the
microstrip.
12. The device of claim 9 wherein the microstrip comprises a
removed region, the removed region providing a transverse slit in
the microstrip.
13. The device of claim 9 wherein the antenna comprises a coil
having a conductive bridge line, at least a portion of the bridge
line being constructed and arranged to facilitate selective removal
thereof to conductively reconfigure the coil for changing impedance
of the antenna.
14. The device of claim 1 wherein the antenna comprises a loop
antenna.
15. The device of claim 1 wherein the antenna comprises a folded
dipole antenna.
16. The device of claim 1 wherein the antenna is formed directly on
the monolithic semiconductor integrated circuit.
17. The device of claim 1 wherein the power source comprises a
battery, the monolithic integrated circuit including electrical
connectors for electrically coupling the battery to the
interrogation receiving circuitry.
18. The device of claim 1 further comprising an encapsulating
package receiving the semiconductor integrated circuit, the
antenna, the interrogation receiving circuitry, and the power
source.
19. The device of claim 18 wherein the package, integrated circuit,
antenna, interrogation receiving circuitry, and power source
comprise a radio frequency identification data tag.
20. The device of claim 19 wherein the radio frequency
identification data tag further comprises transmitter circuitry,
the transmitter circuitry and the interrogation receiving circuitry
being configured to provide a transponder circuit.
21. The device of claim 19 wherein the antenna is separate from the
integrated circuit.
22. The device of claim 19 wherein the package comprises an
identification badge configured to be situated on a user.
23. The device of claim 19 wherein the package comprises a piece of
plastic material.
24. The device of claim 1 wherein the interrogation receiving
circuitry provides the reconfigurable electrical characteristics,
the interrogation receiving circuitry being selectively tunable by
electrically reconfiguring the electrical characteristics.
25. The device of claim 24 wherein the reconfigurable electrical
characteristics comprise a plurality of fixed matching networks, at
least one of the fixed matching networks being configurable into
electrical connection with the receiver circuit in order to
selectively tune the receiver circuit, the receiver circuit and the
antenna thereby realizing the desired receiver sensitivity for the
device.
26. The device of claim 24 wherein the interrogation receiving
circuitry is selectively tunable, the interrogation receiving
circuitry comprising at least one circuit having a selectively
tunable circuit element.
27. The device of claim 24 wherein the interrogation receiving
circuitry is selectively tunable, the interrogation receiving
circuitry comprising memory and software resident in the memory,
the memory and software being operable to realize a software-based
circuit implementation modifiable to selectively tune the
interrogation receiving circuitry.
28. An adjustable radio frequency data communications device for
use with a remote interrogator unit, the device comprising: a
monolithic semiconductor integrated circuit having integrated
circuitry; transmitter circuitry provided on the monolithic
integrated circuit and forming at least part of the integrated
circuitry; an antenna electrically coupled to the transmitter
circuitry and configured to communicate with the remote
interrogator unit; a power source electrically coupled to the
integrated circuitry and configured to generate operating power for
the communications device; and at least one of the antenna and the
transmitter circuitry having reconfigurable electrical
characteristics, the electrical characteristics being
reconfigurable to selectively tune the at least one of the antenna
and the transmitter circuitry within a range of tuned and detuned
states to realize a desired transmitter sensitivity of the
communications device.
29. An adjustable radio frequency data communications device for
use with a remote interrogator unit, the device comprising: a
printed circuit board having printed circuitry; interrogation
receiving circuitry provided on the circuit board electrically
coupled to the integrated circuitry and configured to receive an
interrogation signal from the interrogator unit; an antenna
electrically coupled to the interrogation receiving circuitry, the
antenna configured to receive the interrogation signal from the
interrogator unit and deliver the interrogation signal to the
interrogation receiving circuitry; a power source electrically
coupled to the printed circuitry and configured to generate
operating power for the communications device; and at least one of
the antenna and the interrogation receiving circuitry having
reconfigurable electrical characteristics, the electrical
characteristics being reconfigurable to selectively tune the at
least one of the antenna and the interrogation receiving circuitry
within a range of tuned and detuned states to realize a desired
detuned receiver sensitivity of the communications device.
30. The device of claim 29 wherein the antenna is mounted to the
circuit board.
31. The device of claim 29 wherein the antenna comprises a separate
circuit element mounted to the circuit board and encased in a
package.
32. The device of claim 29 wherein the antenna is constructed and
arranged to be selectively detunable by trimming the antenna.
33. The device of claim 29 wherein the antenna is formed from the
printed circuitry.
34. The device of claim 29 further comprising transmitter circuitry
having at least one circuit with at least one selectively tunable
circuit element electrically reconfigurable to modify tuning of the
transmitter circuitry.
35. The device of claim 34 wherein the at least one circuit
comprises a plurality of fixed matching networks and means for
switching one of the fixed matching networks into electrical
connection with the interrogator receiving circuitry in order to
adjust tuning of the interrogator receiving circuitry and the
antenna.
36. The device of claim 34 wherein the at least one circuit
comprises a detunable circuit element, with the resulting
transmitter circuitry and the antenna having respective mismatched
impedances so as to at least partially detune reception of the
resulting device.
37. The device of claim 34 wherein the at least one circuit
comprises a tunable circuit element, with the resulting transmitter
circuitry and the antenna having respective matched impedances so
as to at least partially detune reception of the resulting
device.
38. A method of adapting a radio frequency data communications
device for use with a remote interrogator unit, the method
comprising the steps of: providing transponder circuitry; providing
an antenna electrically coupled to the transponder circuitry for
communicating with a remote interrogator unit; and selectively
tuning at least one of the antenna and the transponder circuitry
within a range of tuned and detuned states to realize a desired
receiver sensitivity responsive to an interrogation signal
transmitted by the interrogator unit.
39. The method of claim 38 wherein the step of selectively tuning
comprises trimming the antenna.
40. The method of claim 38 wherein the step of selectively tuning
comprises configuring electrical conduction of the transponder
circuit.
41. The method of claim 40 wherein the transponder circuit is
selectively tuned by electrically switching in one or more of a
plurality of fixed circuit networks for realizing the desired
receiver sensitivity of the communication device.
42. The method of claim 40 wherein the transponder circuit includes
a circuit network, the method further including the step of
selectively tuning :the circuit network.
43. The method of claim 38 wherein the transponder circuit
comprises a receiver circuit, the step of selectively tuning
comprises detuning the receiver circuit.
44. The method of claim 38 wherein the transponder circuit
comprises a receiver circuit, the step of selectively tuning
comprises trimming the antenna.
45. The method of claim 38 wherein the transponder circuit
comprises a transmitter circuit, with the step of selectively
tuning comprising detuning the transmitter circuit.
46. The method of claim 38 wherein the transponder circuit
comprises a transmitter circuit, with the step of selectively
tuning comprising trimming the antenna.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority from a U.S. provisional
application Ser. No. (attorney docket MI40-014) filed Jul. 30,
1996, titled "Radio Frequency Data Communications Device with
Adjustable Receiver Sensitivity and Method", and naming Mark E.
Tuttle and John R. Tuttle as inventors.
TECHNICAL FIELD
[0002] This invention relates to radio frequency communication
devices, and more particularly to an adjustable radio frequency
interrogator tag and method of adjusting transponder
sensitivity.
BACKGROUND OF THE INVENTION
[0003] As large numbers of objects are moved in inventory, product
manufacturing, and merchandising operations, there is a continuous
challenge to accurately monitor the location and flow of objects.
Additionally, there is a continuing goal to interrogate the
location of objects in an inexpensive and streamlined manner.
Furthermore, there is a need for tag devices suitably configured to
mount to a variety of objects including goods, items, persons, or
animals, as well as any moving or stationary and animate or
inanimate object. One way of tracking objects is with an electronic
identification system.
[0004] One presently available electronic identification system
utilizes a magnetic field modulation system to monitor tag devices.
A controller or interrogator unit creates a magnetic field that
becomes detuned when the tag device is passed through the magnetic
field. In some cases, the tag device may be alternatively tuned and
detuned in a sequence unique to the tag device in order to
distinguish between a number of different tags, each having a
distinct identify sequence. Typically, the tag devices are entirely
passive, eliminating the need for a portable power supply which
results in a small and portable package. However, this
identification system is only capable of distinguishing a limited
number of tag devices, over a relatively short range, limited by
the size of the resulting magnetic field. Detuning is the means of
encoding the identification number of the tag device or its
data.
[0005] Another electronic identification system utilizes an RF
transponder device affixed to an object to be monitored, in which a
controller or interrogator unit transmits an interrogation signal
to the device. The device receives the signal, then generates and
transmits a responsive signal. The interrogation signal and the
responsive signal are typically radio-frequency (RF) signals
produced by an RF transmitter circuit. Since RF signals can be
transmitted over greater distances than magnetic fields, RF-based
transponder devices tend to be more suitable for applications
requiring tracking of a tagged device that may not be in close
proximity to an interrogator unit. However, when a large number of
devices are utilized, the interrogator unit triggers frequent
wake-up of each device. As a result, responsive signals are
frequently generated. For the case of a battery powered device, the
life of the battery is severely diminished due to frequent
unintentional wake-ups of the device. Therefore, there is a need to
produce tags having different receiver sensitivities, and to
produce tags having either factory or user adjustable sensitivity.
Such constructions are the subject of this invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] Preferred embodiments of the invention are described below
with reference to the following accompanying drawings.
[0007] FIG. 1 is a front view of an employee badge providing the
device of this invention.
[0008] FIG. 2 is a front view of a radio frequency identification
tag of this invention.
[0009] FIG. 3 is a block diagram of an electronic identification
system illustrating communication between an interrogator unit and
the tag of FIG. 2.
[0010] FIG. 4 is a plan view of a monolithic semiconductor
integrated circuit utilized in the device of FIG. 2 illustrating an
integrated circuitry layout configured for use with a hybrid
antenna.
[0011] FIG. 5 is an alternative construction of a monolithic
semiconductor integrated circuit from that depicted in FIG. 4,
wherein the antenna is formed directly on the integrated
circuit.
[0012] FIG. 6 is an enlarged partial view taken generally from
encircled region 6 of FIG. 4 depicting a discretely slit
portion.
[0013] FIG. 7 is an enlarged partial view taken generally from
encircled region 7 of FIG. 4 depicting a stepwise removed
portion.
[0014] FIG. 8 is a diagrammatic side sectional view illustrating
mounting of an integrated circuit, battery and antenna to the tag
device of FIG. 2.
[0015] FIG. 9 is a diagrammatic side sectional view illustrating an
alternative wire bonding technique for mounting the integrated
circuit, battery and antenna to the tag device of FIG. 2.
[0016] FIG. 10 is a diagrammatic side sectional view illustrating
another alternative mounting technique using tape automated bonding
(TAB) of leads to electrically bond the integrated circuit, battery
and antenna together on the tag device of FIG. 2.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0017] This disclosure of the invention is submitted in furtherance
of the constitutional purposes of the U.S. Patent Laws "to promote
the progress of science and useful arts" (Article 1, Section
8).
[0018] According to an aspect of this invention, an adjustable
radio frequency data communications device comprises:
[0019] a monolithic semiconductor integrated circuit having
integrated circuitry; interrogation receiving circuitry provided on
the monolithic integrated circuit forming at least part of the
integrated circuitry and configured to receive an interrogation
signal from the interrogator unit;
[0020] an antenna electrically coupled to the interrogation
receiving circuitry and configured to communicate with the remote
interrogator unit;
[0021] a power source electrically coupled to the integrated
circuitry and configured to generate operating power for the
communications device; and
[0022] at least one of the antenna and the interrogation receiving
circuitry having reconfigurable electrical characteristics, the
electrical characteristics being reconfigurable to selectively tune
the at least one of the antenna and the interrogation receiving
circuitry within a range of tuned and detuned states to realize a
desired receiver sensitivity of the communications device.
[0023] According to another aspect of this invention, an adjustable
radio frequency data communications device comprises:
[0024] a monolithic semiconductor integrated circuit having
integrated circuitry;
[0025] transmitter circuitry provided on the monolithic integrated
circuit and forming at least part of the integrated circuitry;
[0026] an antenna electrically coupled to the transmitter circuitry
and configured to communicate with the remote interrogator
unit;
[0027] a power source electrically coupled to the integrated
circuitry and configured to generate operating power for the
communications device; and
[0028] at least one of the antenna and the transmitter circuitry
having reconfigurable electrical characteristics, the electrical
characteristics being reconfigurable to selectively tune the at
least one of the antenna and the transmitter circuitry within a
range of tuned and detuned states to realize a desired transmitter
sensitivity of the communications device.
[0029] According to a third aspect of this invention, an adjustable
radio frequency data communications device comprises:
[0030] a printed circuit board having printed circuitry;
[0031] interrogation receiving circuitry provided on the circuit
board electrically coupled to the integrated circuitry and
configured to receive an interrogation signal from the interrogator
unit;
[0032] an antenna electrically coupled to the interrogation
receiving circuitry, the antenna configured to receive the
interrogation signal from the interrogator unit and deliver the
interrogation signal to the interrogation receiving circuitry;
[0033] a power source electrically coupled to the printed circuitry
and configured to generate operating power for the communications
device; and
[0034] at least one of the antenna and the interrogation receiving
circuitry having reconfigurable electrical characteristics, the
electrical characteristics being reconfigurable to selectively tune
at least one of the antenna and the interrogation receiving
circuitry within a range of tuned and detuned states to realize a
desired detuned receiver sensitivity of the communications
device.
[0035] According to a fourth aspect of this invention, a method of
adapting a radio frequency data communications device for use with
a remote interrogator unit comprises the steps of:
[0036] providing transponder circuitry;
[0037] providing an antenna electrically coupled to the transponder
circuitry for communicating with a remote interrogator unit;
and
[0038] selectively tuning at least one of the antenna and the
transponder circuitry within a range of tuned and detuned states to
realize a desired receiver sensitivity responsive to an
interrogation signal transmitted by the interrogator unit.
[0039] Referring more particularly to the drawings, FIG. 1
illustrates an employee identification badge 10 embodying this
invention. The badge of this invention in one embodiment has a
radio-frequency data communication device 12 laminated to a back
face of a plastic card 11, wherein the card forms the visible
portion of the badge. Preferably, the communication device 12 is
bonded to the back face of the card by embedding it within a thin
bond line of epoxy-based material. Alternatively, the communication
device 12 is embedded into the plastic card 11. The communication
device 12 has an antenna 14 that is electrically connected with a
transponder silicon-chip integrated circuit 16 to form a
transmitting and receiving device. Additionally, the device has a
battery 18 that is electrically connected to the integrated circuit
in order to power the device when it is transmitting and receiving
radio-frequency (RF) signals between itself and another device.
Preferably, the front face of the badge also has visual
identification features including an employee photograph as well as
identifying text.
[0040] Preferably, the antenna 14 is constructed and arranged to
form a folded dipole antenna, consisting of a continuous conductive
path, or loop of microstrip. The terminal ends of the loop each
form a conductive lead similar to leads 37 in FIG. 4 that
electrically interconnects with a transponder circuit 30 on the
integrated circuit 16, as depicted in use in an alternative
embodiment in FIG. 4 and discussed in greater detail below.
Alternatively, the antenna can be constructed as a continuous loop
antenna 22, as depicted in FIGS. 2-3 and discussed in greater
detail below.
[0041] Preferably, the battery 18 is a thin profile button-type
battery forming a small, thin energy cell more commonly utilized in
watches and small electronic devices requiring a thin profile. A
conventional button-type battery has a pair of electrodes, an anode
formed by one face and a cathode formed by an opposite face.
Exemplary button-type batteries are disclosed in several pending
U.S. patent applications including U.S. patent application Ser. No.
08/205,957, "Button-Type Battery Having Bendable Construction and
Angled Button-Type Battery", listing Mark E. Tuttle and Peter M.
Blonsky as inventors (now U.S. Pat. No. 5,432,827); U.S. patent
application Ser. No. 08/321,251, "Button-Type Batteries and Method
of Forming Button-Type Batteries", listing Mark E. Tuttle as
inventor (now U.S. Pat. No. ______); and U.S. patent application
Ser. No. 08/348,543, "Method of Forming Button-Type Batteries and a
Button-Type Battery Insulating and Sealing Gasket", listing Mark E.
Tuttle as inventor (now U.S. Pat. No. ______). These patent
applications and resulting patents are hereby incorporated by
reference as if fully included herein.
[0042] FIG. 2 depicts an alternative construction for a
radio-frequency data communications device 12' constructed as an
identification postage stamp 20. Device 12' has a
semiconductor-based transponder integrated circuit 16, a battery
18, and an antenna 22. Preferably, the antenna is constructed from
a continuous piece of conductive microstrip configured in the shape
of a square to form a loop antenna. Preferably, the postage stamp
is formed from a thin sheet, or card 21 of plastic material having
a thickness of about 0.005 inches, and a final width and height, of
about 1.25 inches. As was the case for the badge 10 of FIG. 1,
preferably, the device 12' is bonded to a back face of the plastic
card by embedding it in a thin layer of non-conductive epoxy
material. The final thickness is about 0.030 inches. Further
details of the construction will be discussed below with reference
to FIG. 8.
[0043] Preferably, the integrated circuit 16, antenna 22, and
battery 18 form a transponder device capable of transmitting and
receiving RF signals with a radio-frequency interrogator unit 26,
shown in FIG. 3 as radio-frequency communication system 24.
Preferably, the interrogator unit includes an antenna 28, as well
as dedicated transmitting and receiving circuitry, similar to that
implemented on integrated circuit 16. One example of an
interrogator unit implemented in combination with a transponder
unit is disclosed in U.S. Pat. No. 4,857,893, hereby incorporated
by reference. Generally, the interrogator unit transmits an
interrogation signal 27 via antenna 28. The transponder device 12',
in this case stamp 20, receives the incoming interrogation signal
with antenna 22. Upon receiving signal 27, device 12' preferably
responds by generating and transmitting a responsive signal 29.
Preferably, the responsive signal 29 is encoded with unique
information that uniquely identifies, or labels the stamp 20, as
well as any object on which the stamp is affixed.
[0044] With the above described interrogator/transponder
communication system 24, a big benefit is provided over prior art
devices that utilized magnetic field effect systems because a large
number of uniquely identifiable tags can be constructed. With the
old magnetic field effect systems, a passive element tag modified a
magnetic field when moved in proximity to an interrogator unit,
thereby allowing electronic identification and detection of the
tag. However, in order to identify particular tags, each tag was
alternately tuned and detuned in a certain sequence in order to
distinguish it from other tags. It is easy to see that such a
system has at best a very limited ability to discriminate between
tags. In contrast, a large amount of information can be carried on
the responsive signal 29, allowing for detailed description of the
device 12'.
[0045] As a result, such a system 24 can be used, for example, to
monitor large warehouse inventories having many unique products
needing individual discrimination to determine the presence of
particular items within a large lot of products. However, a
significant problem is posed by such implementations where a
battery is used to supply power to the devices since each time an
interrogation signal 27 is received, each device within receiving
range of the signal will "wake up", thereby consuming valuable
power and reducing the life of the battery. Typically, the life of
the device is also reduced commensurately since the battery is
preferably permanently sealed inside either a badge 10, a stamp 20,
or some other similar tag.
[0046] One reason for sealing the battery within the tag is to
simplify the design and construction, as well as to reduce the cost
of producing the tag. Another is to seal the battery within the
tag, thereby protecting it from moisture and contaminants. A third
reason is to enhance the cosmetic appeal of the tag by eliminating
the need for an access port or door otherwise necessary to insert
and remove the battery. When the battery is discharged, the entire
badge or stamp is then discarded. Hence, it is desirable to
maximize the life of the battery by minimizing power
consumption.
[0047] Preferably, the transponder device 12' is electrically
powered by a battery 18. In order to conserve the power supplied
from battery 18, preferably, device 12' goes into a sleep, or
battery conserving stand-by mode of operation during long time
periods where no interrogation signal 27 is received by the device.
Preferably, a low current circuit periodically wakes up the device
every sixteen milliseconds in order to check if any RF signals are
being detected by the device. Upon detection of such signals, the
device fully wakes up, returning it to a full power operating mode.
In order to further extend the life of battery 18, the receiver
sensitivity of the transponder device 12' is preferably tuned over
a range of tuned and detuned states in order to modify the ability
of the device to detect signal 27, and therefore adjust the
tendency for the device to wake up.
[0048] Preferably, the receiver sensitivity of the device is
adjusted by reconfiguring the electrical characteristics
(circuitry) of the circuit forming the transponder device. One way
to adjust the receiver sensitivity is to adjust the sensitivity, or
impedance of the antenna. Another way is to adjust or switch in
different circuit elements in the transponder device, thereby
realizing different circuit configurations. Additionally, the
transmitting sensitivity for the transponder device can be adjusted
in essentially the same manner. Techniques of this invention for
adjusting the transmitting and receiving sensitivities for an
antenna will be discussed below with reference to implementations
depicted generally in FIGS. 4-7. Techniques of this invention for
adjusting the transmitting and receiving sensitivities for circuit
elements of the transponder device will also be discussed below
with reference to implementations depicted generally in FIGS. 4 and
5.
[0049] FIG. 4 depicts the particular construction of integrated
circuit 16 as implemented on the devices 10 and 20 of FIGS. 1 and
2, respectively. As shown in FIG. 4, the integrated circuit is
formed from a single monolithic silicon chip construction wherein
the integrated circuit, or wafer receives an array of transponder
circuits 30, logic circuits 32, memory control logic circuits 34,
and a programmable memory array 36 according to standard
semiconductor wafer processing steps. Additionally, pairs of
conductive die pads 38 and 40 are formed on the integrated circuit
in order to facilitate electrical connection with the antenna 22
and battery 18, respectively. Preferably, circuits 30 are
electrically coupled with the conductive die pads 38 and 40 by way
of sections of conductive microstrip 39 and 41, respectively.
[0050] For illustrative purposes, antenna 22 is depicted in
electrically conductive and bonded relationship with pads 38 via
legs 37, although the preferred assembly technique, illustrated in
FIG. 8 and discussed below, involves a flip-chip epoxy bonding
technique wherein the antenna 22 is actually printed onto the back
face of the plastic card 21 forming the postage stamp 20, after
which the integrated circuit is bonded to the antenna, as well as
to the battery, using a conductive epoxy.
[0051] FIG. 4 depicts the relationship of the transponder circuits
30 relative to antenna 22 which electrically connects directly to
the transponder circuits, and the battery (not illustrated in this
Figure), and which also electrically connects directly to the
transponder circuits. Preferably, the logic circuits 32, the memory
control logic 34, and the programmable memory array 36 electrically
connect with the transponder circuits 30. In this manner, battery
18, once electrically connected to pads 40, powers all of the
circuits 30-36.
[0052] According to one technique for tuning the transceiving
sensitivity of a device 12' carried by a tag, for example stamp 20,
the antenna is laser trimmed after it is formed in order to
reconfigure a conductive portion of the integrated circuit, thereby
modifying the transceiving sensitivity of the device 12' by
changing its impedance. For purposes of this disclosure,
transceiving sensitivity includes transmitter and receiver
sensitivity. Alternatively, just the transmitting sensitivity or
the receiving sensitivity can be tuned. Further alternatively,
separate transmitting and receiving antennas can be independently
tuned. For example, a receive antenna and a separate backscatter
transmit antenna can be used, and for one case, just the receive
antenna is trimmed in order to tune it. Furthermore, for purposes
of this disclosure, tuning refers to either tuning or detuning a
radio-frequency transponder device. Finally, adjustment of the
antenna impedance relative to the impedance of the transponder
circuits imparts a tuning to the combined electrical circuit. For
example, when the antenna impedance matches the transponder circuit
impedance and the two are connected in series, the circuit is
optimally tuned. Similarly, various degrees of impedance
mis-matching produce corresponding levels of detuning.
[0053] Preferably, transponder circuit 30, logic circuits 32 and
memory control logic 34 are implemented as a combination of
hardware circuit elements and software. With respect to the
software components, preferably, the software is implemented in the
programmable memory array 36.
[0054] FIG. 6 depicts one method for tuning the antenna 22 of FIG.
4, wherein a portion of conductive microstrip forming the antenna
is selectively removed along each edge with a laser, forming a
transverse slit 52. The resulting step-width change in the
microstrip antenna causes a change in impedance, thereby changing
the tuned state of the antenna from the originally produced state.
In this manner, a large lot of identical antennas can be mass
produced at the factory, after which the antennas can be laser
trimmed to create batches of antennas having tailored tuned
characteristics, e.g. specific receiving sensitivities.
[0055] Preferably, the antenna 22 of FIGS. 4 and 6-7 is printed
onto the back side of card 21, forming the microstrip loop antenna.
For example, the antenna can be silk screened onto the card with a
conductive polymer thick film. Alternatively, a conductive silver
filled epoxy can be used. Further details of this construction will
be provided below when describing FIG. 8. Alternatively, the
antenna can be formed from a separate piece of conductive material,
for example, from a piece of wire or conductive ribbon that is
glued to the back of the card.
[0056] FIG. 7 illustrates another method for tuning the antenna of
FIG. 4, wherein the microstrip antenna is produced with widened
regions, forming laterally extending pairs of stubs 54. The pairs
of stubs impart changes in the impedance of the resulting antenna
22. Additionally, the stubs facilitate laser removal of portions
56, leaving enshortened stubs 58. As a result, the impedance of the
antenna 22 can be changed, thereby tuning the antenna based on the
amount of conductive material removed from portions 56, as well as
from the number of portions 56 removed from an array along the
microstrip.
[0057] FIG. 5 illustrates a third method for tuning an antenna on a
semiconductor transponder integrated circuit 46 having a
coil-shaped antenna 48 formed directly on the integrated circuit in
the form of microstrip with one of several presently known standard
semiconductor deposition techniques. Antenna 48 is preferably
formed with a conductive bridge line 50 similar to conductive
microstrip lines 39 and 41 that shunts conduction between adjacent
coils of the antenna. After the antenna is produced, at least part
of the conductive bridge line 50 can be removed, either
mechanically or by laser trimming in order to tune the antenna to a
desired state. By selectively cutting the bridge line 50, the
effective conducting length of the antenna is modified, realizing
one or several possible length antennas defined by the number and
size of each coil, and any remaining portion of the bridge.
Preferably, an insulating layer of material is deposited on top of
conductive leads 41 during manufacture in order to insulate the
leads from shorting out coils on the antenna 48. Alternatively,
numeral 46 of FIG. 5 can represent a printed circuit board having
integrated circuitry and hybrid circuit elements attached to the
circuitry, forming the circuits 30-36 and antenna 48. For a device
of this invention implemented on a printed circuit board, the
inventive contribution consists of intentionally detuning the
transponder sensitivity of the tag device.
[0058] For the case where the receiver sensitivity of the device is
adjusted by reconfiguring the transponder circuits, the receiver
sensitivity can be modified by electrically modifying the receiver
circuit on the integrated circuit itself. For example, a plurality
of parallel circuits, each having a different impedance or
amplification factor are alternately switched into an electrically
conductive configuration within the transponder circuit.
Essentially, different fixed matching networks can be alternately
switched into connection within the circuit.
[0059] One way to achieve the switching is to provide temporary
contact connections on the integrated circuit (not shown) for
forming a temporary electrical connection at the factory, allowing
for factory setup of one of the matching networks within circuits
30 to realize a specific tuned condition for a transponder device
12. For example, an array of resistive and/or capacitive elements
can be provided on parallel circuit legs, each configured with a
physical switch for connecting and disconnecting the leg from the
transponder circuit, such that each leg imparts a different circuit
impedance, and hence, a different tuning. Another way is to
implement a software switching routine that allows either factory
or user switching of different circuit implementations within the
transponder circuits 30, with actual circuit elements or with a
software routine implemented in memory 36 and triggered by
interrogation signals 27 received from the interrogator unit 26
depicted in FIG. 3 to realize a software-based circuit
implementation. Additionally, each circuit leg can have an
amplifier configured to impart a distinct tuning level to the
circuit when switched into connection with the circuit. Hence, the
transponder circuit realized on the integrated circuit is modified
to change the circuit impedance, thereby realizing a different
receiving sensitivity for the device. The same technique can be
used to tune the transmitting sensitivity. Additionally, a hybrid
element such as a trim pot can be connected to the circuits 30 of
the integrated circuit to allow adjustment, or tuning of the
circuits by either a manufacturer or a user.
[0060] Another reason for providing a tuning feature on RF data
communication devices such as tags 10 and 20 is to allow a
manufacturer to produce large lots of identical integrated circuits
and antennas, thereby enabling a cost savings resulting from large
scales of production. Furthermore, by producing runs of identical
devices, variables can be better controlled, enabling production of
more uniform product which increases the amount of acceptable
yield. After manufacture, the integrated circuits and/or antennas
can be tuned by one of the techniques of this invention in order to
create tuned tag devices having particular receiving and/or
transmitting sensitivities.
[0061] For example, stamps 20 can be mass produced, then the
antenna 22 can be tuned to impart one of three receiver
sensitivities of 5 feet, 20 feet or 100 feet. One customer may need
tags having only one of the above operating ranges. Another
customer may need all three, placing the least sensitive tags on
objects where frequent inadvertent wake up calls from an
interrogator are undesirable. When it is necessary to wake up the
device, the interrogator is positioned within the five foot range
in order to activate the device, resulting in a responsive signal
29. Additional applications requiring employee badges 10 having
varying degrees of receiver sensitivity can easily be
envisioned.
[0062] FIG. 8 shows an exemplary technique for assembling the
postage stamp 20. The same technique can be used to assemble the
badge 10 or any other similarly constructed tag having a rigid
support or substrate similar to plastic cards 11 and 21. First,
antenna 22, conductive pads 66-68 and conductive microstrip leads
69 are printed onto a back face of the sheet of material.
Preferably, the above elements, or conductors are simultaneously
printed onto the back of a large sheet of plastic material with a
conductive silver printed thick film. Later, the cards are
individually separated (after complete assembly), or cut from the
sheet. Pads 66 form enlarged connection points for the antenna 22,
in contrast to the pads 37 formed directly from the end portions of
the antenna 22 in FIG. 4. Next, the sheet is positioned front face
down onto a rigid support plate 62. Then integrated circuit, or
chip 16 is mounted to pads 66 and 67 with conductive beads of epoxy
70. Finally, the battery 18 is bonded along its bottom face with a
bead of conductive epoxy 70 to the sheet, on each card, after which
conductive epoxy 70 is used to electrically connect the opposite
terminal or top of the battery with a corresponding conductive die
pad 68. The antennas and electrical components are then
electrically tested and/or trimmed, if necessary, prior to being
encapsulated.
[0063] Subsequently, a bead of hot melt glue forming a dam 64 sized
to conform generally to the outer peripheral shape of the sheet 21
is placed over the back of the card. The dam functions as an outer
template while a thin layer of non-conductive epoxy (not shown) is
applied to the back of the sheet 21, preferably hermetically
sealing in (or encapsulating) the integrated circuit, antenna and
battery. Subsequently, the sheet is separated, or singulated to
form separate cards. In this manner, a large number of devices are
assembled onto a single sheet, after which they are separated.
Preferably, the thin coat of epoxy consists of a coating, barely
thick enough to cover over the components forming the device 12'.
One benefit provided by this construction technique is the
elimination of any visible bumps in the tag which can result when
constructing the tag by heat sealing two or more pieces of plastic
card together to trap the device 12' therein. However, a lesser
preferred construction of this invention envisions forming the tag,
e.g. badge 10, stamp 20, or some other tag, with such a heat sealed
sandwich of plastic cards. Furthermore, for constructions using a
printed circuit board, the tag can be formed from a case inside of
which the board is mounted.
[0064] Preferably, the above technique for mounting integrated
circuit 16 to card 21 consists of a flip-chip mounting technique.
One example of a flip-chip mounting technique is disclosed in
pending U.S. patent application Ser. No. 08/166,747, "Process of
Manufacturing an Electrical Bonding Interconnect Having a Metal
Bond Pad Portion and Having a Conductive Epoxy Portion Comprising
an Oxide Reducing Agent", listing Rickie C. Lake and Mark E. Tuttle
as inventors (now U.S. Pat. No. ______), and herein incorporated by
reference.
[0065] FIG. 9 depicts an alternative method for electrically
connecting the integrated circuit 16 to the antenna 22 and battery
18 with conductive wires. In this construction, the integrated
circuit 16 is adhesively bonded to the back face of card 21,
between the bonding pads 37 of the antenna 22 and the battery 18.
Similarly, the battery 18 is bonded along a bottom face to pad 68.
Subsequently, a wire 76 and 78 is used to connect each of the
integrated circuit pads 38 and 40, respectively, to antenna bonding
pads 37 and the top and bottom of battery 18, respectively.
Preferably, each wire is soldered to the associated pads and
battery. Alternatively, the wires can be electrically mounted using
conductive epoxy.
[0066] FIG. 10 depicts another alternative method for electrically
connecting the integrated circuit 16 to the antenna 22 and battery
18 with conductive leads 80 and 82, respectively. Preferably, one
end of each lead 80 and 82 is bonded to a pad 38 and 40 on the
integrated circuit, respectively, and the other end is bonded to
pad 37, and pad 67 and the top of battery 18, respectively, using
conductive epoxy. Alternatively, the leads can be soldered at each
end to the respective components. Preferably, the battery is bonded
to the back face of card 21 by applying conductive adhesive between
the battery and pad 68. Preferably, the integrated circuit is
bonded along a bottom face to the back side of card 21.
[0067] In compliance with the statute, the invention has been
described in language more or less specific as to structural and
methodical features. It is to be understood, however, that the
invention is not limited to the specific features shown and
described, since the means herein disclosed comprise preferred
forms of putting the invention into effect. The invention is,
therefore, claimed in any of its forms or modifications within the
proper scope of the appended claims appropriately interpreted in
accordance with the doctrine of equivalents.
* * * * *